Photographic material for making colored prints



Dec. 11, 1934. M. w. SEYMOUR I PHOTOGRARHIC MATERIAL FOR MAKING COLORED PRINTS Filed Feb. 29, 1932 file/momma @ELAT/NE LAYER CONTAINING SILWIR loo/o5 finw/yaA BAsIc DYE Ammo 77mm Patented Dec. 11,1934

. UNITED STATES PATENT OFFICE.

PHOTOGRAPHIC' MATERIAL FOR MAKING COLORED PRINTS "Merrill W. Seymour, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New York Application February 29, 1932, Serial No. 595,971 2 Claims. (Cl. 95-7) This invention relates to a material for makand'washed for hour in cold-running water. ing photographic prints of the type known as 10 c. c. of the remelted washed emulsion coated carbon prints and particularly to colored caron a 5in. 7in. plate will provide a satisfactory bon prints. example. A transparent blue-green coating will The use of bichromated gelatin layers for be obtained by this procedure. A plate'thus. 5 producing photographic positives by the methcoated is now bathed 5 minutes in the follow-' d called the carbon process has been known ing solution and dried:

2:; tr: assistants: arm. g i 5 bichromated layers and several have introduced g g g 50,11 concen m e 1 fi 1 10 silver salts with or without pigments. These V e prior bichromated layers were sensitive how- If portions, of this sensitized plate are exever only to blue and violet light. posed through the glass side behind the same I have found a simple method by which a negative for, say, three minutes to a E-ampere bichromated gelatin layer may be optically arc lamp. at one foot for one portion and three- 15 sensitized to the longer wavelengths and at minutes to a 500-watt tungsten filament lamp the same time contain a suitable dye for a at one foot for the other portion, it will be found color print. I have moreover found that a after development that the print made with layer made according to my invention has the Tungsten lamp is somewhat denser than the hitherto unknown proper y o giving a other. This is of course contrary to the be- 2G trolled degree of contrast by simply varying havior of the older bichromated layers and the quality of the printing light. shows a marked increase in the sensitivity of My invention is carried out by adding to a the layer for the longer wavelengths. It is bichromated gelatin a quantity of silver iodide understood of course that these prints are dehaving a dye adsorbed to it. In practice the veloped, as for the usual bichromated prints, in Same result y be attained y c g a upwater at about 110 F., producing transparent port with an emulsion containing the dyed silblue-green relief images with the particular veriodide and 'then sensitizing this emulsion dye mentioned in the example. by bathing in bichromate. In either case the The sensitivity of the bichromated gelatin to result will be the same. all portions of the visible spectrum may be read- 30 Referenc i m to he cc mp nyin ily shown by exposing to light through suitable drawing, the single figure of which shows on filters. The following experiment will illustrate. an eXaggelated Scale a SeCtiOIl Of a p fl ph A plate sensitized as above was exposed through element embodying my invention. In this figthe glass side behind the series of neutral den- E, pp which y be of y material sities ascending in uniform steps of 0.2 and cov- 35 is indicated at 1 and this carries a layer 2 of ered in difierent portions by Wratten filters 29 bichromated gelatine containing. silver iodide (red), 61 (green), and 49 (blue). Exposure was having basic dyesstrongly adsorbed thereto. for 12 minutes to are lamp at one foot and a The method of making and the character print was developed in water at 110 F. The

of these materials are more fully described relief image of blue-green color was obtained 40 hereinafter. showing five steps for the red filter, three steps As a specific example plates may be prepared for the green filter and five steps for the blue from the following formula: filter. The sensitivity of the bichromated ge1a-- I tin to all portions of the visible spectrum is thus clearly indicated. 45 Gelatin, 12.5% solution s- 40 c. c. In this experiment the contrast of image was Water 30 c. 0. very high through the green filter, but moderate Turquoise blue G, 1%; 20 c. 0. through the red and blue filters. The contrast Silver nitrate, 10% 15 c. c. is therefore reduced in those regions in which II the emulsion absorbs light most strongly. With 50 g the plates described, the dye absorbs strongly in Potassium iodide, 10% 18 c. c. the red region and to some extent, probably, in Water 22 c. c. the violet. The silver iodide absorbs strongly in II is slowly poured into I while the mixture is the violet region. Neither substance absorbs to stirred. The resulting emulsion is set, shredded, so great an extent in the green region. 55

It is therefore apparent that the method I have just described may be made the basis of a means for controlling the contrast of a carbon print in a manner which has not heretofore been possible.

This may ;be done by varying the spectral quality or color 01' the printing light so as to attain either .a high contrast or a lower degree of contrast. If a high contrast is required, one prints the bichromatedlayer sensitized as described by light from a region only slightly absorbed by the emulsion. By admitting a lesser amount of light of this color and admitting more 01! the light which is more strongly absorbed by the emulsion (complementary in color) the contrast is reduced. To secure the minimum contrast one would print'entirely to light the color complementary to the emulsion. In the example described, a red filter would be indicated, for example.

I propose to app y the above method of carbon printing to the makingof prints from black and white negatives and making color prints from color separation negatives or directly from color negatives on screen plates or direct subtractive color plates. My invention oflers marked ad-,

vantages for the well-known method of makingsuperposed color transparencies.

As an example of making a color print from an autochrome negative, I first make a print from a negative on to ablue-green emulsion of the kind described using a red filter. I then make a print on to a magenta emulsion using a green filter and on to a yellow using a blue filter. The three prints, having been developed in warm water and dried are superposed in register to form a colJr positive which may be either a transparency or a paper print.

A large number of dyes, particularly basic dyes, are available for use to yield a large variety of colors. In fact, I have found that many, if not most, basic dyes that are strongly colored and are strongly absorbed to silver iodide are operative, even though they are not in themselves sensitizers for silver halides in the ordinary photographic process involving a brief exposure to light and a subsequent development of a silver image by means of. an alkaline reducing solution. These dyes, 01' course, vary widely in theirefiiciency but the operative dyes for this purpose are so numerous and well known that it would be almost impossible to give a complete list. While I have illustrated my invention' with a singletdye and a single formula,

it is strongly adsorbed to the silver iodide and is permanently retained in the developed relief image and that it extends the color sensitivity of the layer to all colorsoi' the visible spectrum.

2. A permanently colored light-sensitive layer comprising bichromated gelatine and silver iodide having adsorbed thereto a strongly colored basic dye which is permanently retained in the developed relief image;

MERRILL W. SEYMOUR. 

